Our existing model for myocardial and ventricular mechanics will be refined to include an isotropic component of elasticity, passive and active viscoelasticity, non-cylindrical geometry, pathological fiber organization, myocardial blood flow, myocardial oxygen demand, and effects of activation pattern. The model will be used in conjunction with ultrasonic kinematic data to determine performance parameters. The physiological relationships between phasic coronary arterial and venous pressure and blood flow, aortic input impedance and ventricular dimensions will be determined. A mathematical and physical model of myocaridal blood flow will be developed incorporation vessel collapse. Experimental techniques will be developed to measure vascular distensibility in man. RF backscatter from the myocardium will be investigated both experimentally and mathematically with the idea of determining the stress field. Theoretical models of wave propagation in arteries and aortic input impedance will be checked against experimental data.